Paper feeding mechanism

ABSTRACT

A paper feeding mechanism includes a base, a driven roller, an active roller, a shaft, and a plurality of torsion elements. The shaft is disposed on the base, and the torsion elements are coaxially connected to the shaft with a first and a second force arm pressing against the rotational axial position of the driven roller and the base respectively. The torsion elements provide a normal force to the driven roller, so that the driven roller may press against the active roller constantly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 095214058 filed in Taiwan, R.O.C. on Aug. 9, 2006, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a paper feeding mechanism of a peripheral, and more particularly, to a paper feeding mechanism capable of providing a normal force to press and pick up paper.

2. Related Art

Generally speaking, the operation of an office relies much on the use of paper, for example, business letters and various documents, so a paper feeding mechanism of a peripheral such as a printer, plotter, fax, scanner, copier, multi function peripheral (MFP) is required to facilitate the scan, print, copy, or fax of paper. Considering the high demand for paper, the output quality and operating efficiency are always the key issue of development for the peripheral manufacturers. However, the currently used peripherals such as copiers usually use mechanisms such as rollers to transmit paper, so as to achieve a smooth transmission without folding paper when feeding, scanning, printing, or ejecting paper.

The design of roller structure in a conventional paper feeding mechanism has a function of separating and feeding paper when transmitting paper. For example, the driven roller in the paper feeding mechanism usually adopts a compression spring or blade spring to provide a normal force to the device. However, in a confined space, the travel is insufficient and the force cannot be easily controlled. Moreover, due to manufacturing and processing techniques and the limitation in the manufacturing cost and the assembly in the product line, the roller structure of the paper feeding mechanism cannot be installed and repaired conveniently and rapidly. Accordingly, the manufacturing cost is increased. Besides, the roller positioning structure of the conventional paper feeding mechanism influences the repair, replace and maintenance of the roller structure, and cause an increase in the manufacturing cost and the difficulty in assembling.

Furthermore, if an external force is applied to an axis under non-uniform pressure or different coaxial elements, a torque or bending moment is generated on the axis. Thus, angular velocities of the paper getting out of driven roller and active roller are inconsistent, thereby causing a paper jam or resulting in the deformation or break of the bear due to the improper use.

Referring to FIG. 1, a paper feeding mechanism disclosed in U.S. Patent Publication No. U.S. Pat. No. 6,978,998 is shown. As shown in FIG. 1, the paper feeding mechanism has a driven roller 33 a, an active roller 34 a, and a transmission shaft 36 a. The active roller 34 a is coaxially connected to the transmission shaft 36 a. The driven roller 33 a is in rolling contact with the active roller 34 a. Moreover, the roller positioning structure has a flexible shaft 31 a pivoted at an opening 333 a. The flexible shaft 31 a is integrally formed with a flexible arm 32 a. The flexible shaft 31 a is made of a rigid material and has a spring profile winding axially and extending outwards. The flexible arm 32 a is made of rigid material and has resilience. When the active roller 34 a applies a pressure on the driven roller 33 a, the third portion 322 a of the flexible arm 32 a provides a counterforce to the first portion 321 a of the flexible arm 32 a.

Referring to FIG. 2, a design of the partial structure of a conventional driven roller is shown. As shown in FIG. 2, the conventional paper feeding mechanism includes a driven roller 11 b, an active roller 12 b, and a garter spring 15 b. A garter spring 15 b is embedded in a driven roller shaft 14 b. When a paper 40 b is guided to be passed through an interval between the driven roller 11 b and the active roller 12 b, the garter spring 15 b provides only a normal force to the driven roller shaft 14 b. However, the normal force cannot be uniformly applied to the driven roller shaft 14 b, so that an offset space is formed for the driven roller 11 b, which cause the swaying of the driven roller 11 b, thus affecting the output quality of paper.

Referring to FIG. 3, a driven roller device and an elastic structure thereof is disclosed in U.S. Patent Publication No. 2005/0012264, which includes a driven roller 11 c, an active roller 12 c, a driven roller shaft 14 c, and torsion elements 30 c. The torsion elements 30 c are wound around the driven roller shaft 14 c, and the two force arms are respectively disposed on a baffle plate 50 c. Therefore, when the active roller 12 c and the driven roller 11 c roll with respect to each other, the torsion elements 30 c generate a tension and a normal force to the driven roller 11 c, so as to resist the pressure applied by the active roller 12 c. However, the design of resilient structure may still generate an ineffective moment, thus dispersing the normal force intended to be applied to the driven roller 11 c.

SUMMARY OF THE INVENTION

The conventional art cannot effectively reduce the volume to be adapted to a narrow space, and a component force is generated from the normal force, such that the normal force cannot completely act on the driven roller, thus resulting in an unsmooth paper feeding and folding paper. Moreover, the installation is inconvenient and the parts are complicated, so that the manufacturing cost increases. In view of the above problems, the present invention is directed to provide a paper feeding mechanism. The paper feeding mechanism of the present invention comprises a base, a shaft, and a plurality of torsion elements. The base is provided with a driven roller, and an active roller is disposed corresponding to the driven roller, wherein the driven roller presses against the active roller constantly. The paper feeding mechanism comprises a shaft disposed on the base. A plurality of torsion elements is coaxially connected to the shaft, wherein each of the torsion elements has a first and a second force arm pressing against the rotational axial position of the driven roller and the base, respectively.

The paper feeding mechanism disclosed in the present invention has a reduced volume and can be applied to a narrow space and provide a normal force between the paper and the driven roller. The normal force can completely act on the driven roller, so as to achieve a close contact between the driven roller and the active roller and eliminate the ineffective component force. Further, the driven roller is characterized by bumps disposed thereon, which is advantageous for arranging paper to smoothly feeding the paper. Moreover, the parts are simple, thus saving the material and assembling processes. Therefore, the present invention has an advantage of low cost.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is an exploded structural view of the device for applying normal force to the roller according to the conventional art.

FIG. 2 is a combined view of the device for applying normal force to the roller according to another conventional art.

FIG. 3 is a schematic view of the implementation of another conventional art.

FIG. 4 is an exploded structural view according to a first embodiment of the present invention.

FIG. 5 is a combined structural view according to the first embodiment of the present invention.

FIG. 6 is a combined structural view according to a second embodiment of the present invention.

FIG. 7 is a schematic view of the position of the stopper according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the paper feeding mechanism disclosed in the present invention, the paper feeding mechanism can be applied, but not limited to, printers, plotters, faxes, copiers, MFPs, scanners, and so on. The present invention can be applied to any equipment having a paper feeding mechanism to input/output paper.

Please refer to FIG. 4 of an exploded structural view of a paper feeding mechanism 10 according to a first embodiment of the present invention. As shown in FIG. 4, the paper feeding mechanism 10 includes a driven roller 11, an active roller 12, and a base 50. The base 50 has a driven roller 11 and a driven roller shaft 14. The driven roller 11 and the active roller 12 are disposed in correspondence with each other. The driven roller shaft 14 is disposed in the rotational axial direction of the driven roller 11 and passes through the driven roller 11, and a transmission shaft 13 passes through the active roller 12.

Further, two shafts 15 adjacent to one side of the driven roller shaft 14 are joined with the base 50. One of the two opposite ends of each shaft 15 is a free end, and the other is fixed on the base 50. Moreover, the shafts 15 are parallel to the axial direction of the driven roller shaft 14.

The paper feeding mechanism 10 also has a plurality of torsion elements 30 disposed between the driven roller shaft 14 and the base 50. The torsion elements 30 can be torsion springs. Each of the torsion elements 30 has a first force arm 31 and a second force arm 32 extending outwards with respect to the torsion element 30.

Moreover, the active roller 12 rolls by the use of the transmission shaft 13. The driven roller 11 is in rolling contact with the active roller 12 and presses against the active roller 12 constantly. The torsion elements 30 are coaxially connected to the shaft 15, such that the first force arm 31 and the second force arm of 32 of each torsion element 30 respectively extend outward to any other places. Moreover, clamping portions 51 are disposed on the base 50 corresponding to the torsion elements 30. The first force arm 31 and the second force arm 32 of each torsion element 30 respectively press against the driven roller shaft 14 and the clamping portion 51 of the base 50.

Please refer to FIG. 5 of a combined structural view of the paper feeding mechanism 10 according to the first embodiment of the present invention. As shown in FIG. 5, when the active roller 12 starts to roll by the use of the transmission shaft 13, the driven roller 11 is driven to roll in sync, so as to guide the paper to advance. When the paper is passed through the interval between the active roller 12 and the driven roller 11, the active roller 12 applies a pressure to the driven roller 11. At this time, the torsion elements 30 are disposed on the clamping portions 51 on the base 50 by the second force arm 32. The base 50 provides a supporting force to the torsion elements 30. A s the first force arm 31 of the torsion elements 30 are disposed on the driven roller shaft 14, the base 50 provides an acting force to the driven roller shaft 14, so that the driven roller 11 presses against the active roller 12 constantly to maintain a rolling contact. Due to the arrangement of the torsion elements 30, the driven roller 11 is provided with bumps, so as to facilitate feeding paper and meanwhile provide a normal force between the paper and the active roller 12, such that the normal force completely acts on the active roller 12 thus eliminating the generation of component force. Moreover, the torsion elements 30 are coaxially connected to the shaft 15 on the base 50, so that the swaying of the torsion elements 30 does not occur and the torsion elements 30 can be joined steadily, and also the position of the driven roller 11 does not offset excessively. Therefore, the pressure applied by the active roller 12 can be balanced under the circumstance that the position of the torsion elements 30 does not offset excessively and a normal force can be provided.

Please refer to FIG. 6 of a combined structural view of the paper feeding mechanism 10 according to a second embodiment of the present invention. As shown in FIG. 6, the two opposite ends of the shaft 15A are joined with the base 50, and a plurality of torsion elements 30 is coaxially connected to the shaft 15A.

Please refer to FIG. 7 of a schematic view of a position of a stopper according to the present invention. As shown in FIG. 7, a stopper 53 is further disposed on the base 50 of the present invention in a limited position adjacent to the driven roller shaft 14. When the driven roller 11 presses against the active roller 12, the driven roller 11 can only move in the limited position. The stopper 53 can confine the driven roller 11 moving within a limited range. The stopper 53 and the base 50 are integrated into one piece.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

1. A paper feeding mechanism, comprising: a base having a driven roller disposed thereon the base and an active roller disposed corresponding to the driven roller, the driven roller pressing against the active roller constantly; a shaft disposed on the base; and a plurality of torsion elements coaxially connected to the shaft; wherein each of the torsion element has a first force arm and a second force arm respectively pressing against the rotational axial position of the driven roller and the base.
 2. The paper feeding mechanism as claimed in claim 1, wherein a plurality of clamping portions are disposed on the base corresponding to the torsion elements to be pressed against by the torsion elements.
 3. The paper feeding mechanism as claimed in claim 1, wherein the active roller is rolled by a transmission shaft.
 4. The paper feeding mechanism as claimed in claim 1, wherein a driven roller shaft is disposed on the base in the rotational axial direction of the driven roller and passes through the driven roller.
 5. The paper feeding mechanism as claimed in claim 4, wherein the shaft is parallel to an axial direction of the driven roller shaft.
 6. The paper feeding mechanism as claimed in claim 1, wherein the base further comprises a stopper disposed in a limited position adjacent to the driven roller shaft, and when the driven roller press against the active roller, the driven roller only moves to the limited position.
 7. The paper feeding mechanism as claimed in claim 6, wherein the retaining element and the base are integrally formed.
 8. The paper feeding mechanism as claimed in claim 1, wherein the torsion elements are torsion springs. 